Dimplex Incomplete Combustion / Flue Gas Spillage

Boiler casing or flue area shows signs of soot or black staining

Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Blocked Dimplex flue, Incorrect gas/air ratio due to faulty Dimplex gas valve, Damaged burner or seals in Dimplex combustion chamber, Insufficient ventilation in boiler cupboard (for open-flued models)

How to Fix / Troubleshooting

Safety first: This is potentially dangerous. Turn off the boiler immediately and do not use it. Ventilate the area and contact a Gas Safe–registered engineer.

User actions:

Do not clean away evidence: Leave soot deposits visible for the engineer to assess.
Check CO alarm: Ensure a carbon monoxide alarm is installed and functioning in the boiler area.

Professional repair:

Inspect and clear the Dimplex flue system.
Check burner, seals, and gas valve settings, and perform full combustion analysis.

Repair Difficulty

Professional Required 5/5

Required Part

Dimplex burner and flue system

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